linux-kernel - RE: [PATCH 1/1] perf,tools: add time out to force stop endless mmap processing

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Date:	Fri, 12 Jun 2015 14:42:53 +0000
From:	"Liang, Kan" <kan.liang@...el.com>
To:	David Ahern <dsahern@...il.com>, Andi Kleen <andi@...stfloor.org>
CC:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Huang, Ying" <ying.huang@...el.com>
Subject: RE: [PATCH 1/1] perf,tools: add time out to force stop endless mmap
 processing


> 
> On 6/11/15 12:47 PM, Andi Kleen wrote:
> >> Can you elaborate on an example? I don't see how this can happen
> >> reading a maps file. And it does not read maps for all threads only
> >> thread group leaders.
> >
> > This is with a stress test case that generates lots of small mappings
> > at very high speed and frees them again. So the maps file keeps
> > changing faster than the proc reader can keep it and it can end up
> > with a live lock.
> 
> Can you pass it along? I'd like to see how the task_diag proposal handles it.
> 
> https://github.com/dsahern/linux/commits/task_diag-wip

Hi David,

I tried the task_diag on my platform, but it shows error message when I
run perf top. " Message handling failed: rc -1, errno 25".
And it looks perf top failed to get maps information.

  20.88%  [unknown]         [.] 0x00000000004992c4
   6.77%  [unknown]         [.] 0x000000000048f9e7
   4.92%  [unknown]         [.] 0x000000000043789c
   4.68%  [unknown]         [.] 0x0000003002f32918
   4.31%  [unknown]         [.] 0x00000000004992d6
   1.85%  [kernel]          [k] _raw_spin_lock
   1.84%  [unknown]         [.] 0x00000000004d8190
   1.84%  [unknown]         [.] 0x00000000004378ad
   1.40%  [kernel]          [k] clear_page_c_e
   1.23%  [unknown]         [.] 0x00000000004992d0
   1.23%  [unknown]         [.] 0x00000000004378cf

I installed the task_diag kernel and libnl3-3.2.22-3.

Thanks,
Kan

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